Homologues of Arabidopsis Microtubule-Associated AIR9 in Trypanosomatid Parasites: Hints on Evolution and Function.

AIR9 is an essential microtubule-associated protein from Arabidopsis. Sequence similarity searches indicate homologues of AIR9 in land plants and in excavate protists, including trypanosomatid parasites and Trichomonas. The AIR9-like protein from Trypanosoma brucei was recently detected in the proteome of the trypanosome flagellum, raising the possibility that trypanosomatid AIR9-like proteins also associate with microtubules. Because microtubule functions are essential to the viability of trypanosomatid parasites AIR9-like proteins may be exploited as drug targets without homology in humans. We further discuss the unexpected phylogeny of AIR9-like proteins from plants and protozoans.